asp.net windows forms - best place to persist application data

For Windows.Forms, I have an application that needs to get a unique install id for each install from my server, and then persist this data so once registered开发者_如何学JAVA, the install ID is included on all communications back to the server. The application is in occasional contact with the server.

How can I persist this data on the client in a way that is not easily tampered with?

First, you should note that if the data is on the local file system and your application can read and write it, it will always be possible for a determined user to tamper with it... perhaps not easy, but possible nonetheless.

That said, there are a number of options you could consider, including (but not limited to) :

• encrypting the data with a key defined in your assembly : pretty safe is the user has no programming skills, but an advanced user could disassemble your app to find the key. Obfuscation could make it harder to extract the key, but not impossible.
• using an isolated storage : I'm not sure whether the data is encrypted or not, but at least it's not easily found, hidden in a deep folder hierarchy... Not so safe is the user knows where to look, however
• writing the data in a binary format, which makes it harder to read or modify for a non expert user
• using a piece of native code to encrypt the data : similar to the first option, but a native DLL is harder to disassemble than a .NET assembly, so it requires more skills to find the key

Again, all these approches are not bulletproof : as long as your program can access the data, an advanced user could always reverse engineer it and do the same...

You could save the data in the windows registry. You'll use the [HKCU\Software\YourAppName] hive key if it's a per-user setting, or [HKLM\Software\YourCompany] if it's a global setting. However, the data would need to be encrypted, because its trivila to get the values in these keys